I've made some 16x16 icons. Don't blame me if they are ugly, I usually code and don't design stuff. Try to make or google something better, while the latter option has some license fun included for sure.

Pending (0 confirmations): http://www.abanbytes.eu/files/btc/pending.png
Unconfirmed: http://www.abanbytes.eu/files/btc/unconfirmed.png
Confirmed: http://www.abanbytes.eu/files/btc/confirmed.png

License: You are free to do with these icons as you wish, including selling, copying, modifying etc.

Yours
David